More than 900 veterans of the Defence Forces have passed through homeless hostels in Dublin, Westmeath and Donegal since 2005.
Many of those men and women served overseas in conflict zones, as well as at home during the Troubles.
This afternoon, the Organisation of National Ex-Service Personnel launched an appeal to raise funds for its hostels.
Retired Sergeant Major Richard Dillon, manager of Brú na bhFiann, explains what causes so many defence forces veterans to enter homelessness.
He said: "Those who are leaving the Defence Forces and either don't have a pension or they're of the lower grades within the Defence Forces and their pensions aren't particularly large.
"It's a lack of affordable social accommodation or even private affordable...family breakup, marital breakup, those suffering with minor mental health issues."
The Defence Forces are 1,700 officers short of what it should be.
That is according to Brendan Smith, the chairman of the Oireachtas defence committee, which will focus on pay in the force today.
The representative association PDFORRA will address the committee on existing contracts for soldiers, sailors and aircrew.
Deputy Smith said so many people leaving the organisation is a major concern.
He said: "The strength should be at 9,500 but it's only at 8,800 at the moment - what we would like to see is 10,500 strength enlisted.
"The recruitment policy has not a proper retention policy so young persons who join the army and navy but in many instances are leaving young."